Improvement in rotary pumps



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A. H. 'KNAPR OF NEEDHAM, MASSACHUSETTS.

Letters Patent No. 92,842, dated July 20, 1869;- lmtedcted'luly 17, 1869.

IMPROVEMENT IN ROTARY PUMPS.

.The Schedule referred to in these Letters Patent and x'nakng part of the same.

' pla-te of the case being removed, so as .to show an end view of the piston-wheel and its bntment.

Figure 2, a vertical section.l thereof through the centre lines of the piston'and bntment-shafts.

Like letters designate corresponding parts in both figures.

My present improvements approximate to the kind of rotary pumps in which'a revolving piston-wheel is employed, gearing into a rotary bntment, which re volves therewith, and gives passage to the pistons thereof, by means of concavities in its periphery.

v,The genera-l vconstruction and operation arethe same as set forth in Letters Patent granted to me ou the ,17 th day of November, 1863, and, therefore, not necessary to repeat here.

In the foimer Let-ters Patent-the bntment performs little or no rwork, but is intended merely to give passage to the pistons, and theoretically this would seem to be the proper construction, since the bntment is driven by transmitted power, involving friction and wear, in proportion to the amount of power required to turn it,'and when itl merely serves the purpose of a bntment, no further power is required than simply to overcome its own inertia and friction. But practically it has proved that ywhere the bntment performs no work, it vibrates forward and backward in its path of revolution, as much as the slight play of its gearing will permit, producing much jar, lespecially when the pump is working at a high speed and under heavy pressure, the jar rapidly increasing with the increase of speed.

This, if not-actually destructive, at least is more or lessinjnrious and very undesirable.

This vibratioinowin'g to slight variations inthe quantity of water thrown in different parts ofthe revolution of the piston, which want of perfect uniformity of a nearly inelastic i'luid, produces alternate pulsations of action and reaction in the flowing stream, operates in such a manner or direction upon the bntment as to throw it forward ofthe action of the piston, in the alternate pulsations of the water.

`I remedy this objectionable action ofthe pump by' extending one (or more) of the teeth of each geared portion a of the bntment I outward beyond the remainder of the teeth, as at fr 4', fig. l, and-only these extended teeth iit the inside of the case A, while there is a narrow space left between the extremities of the other teeth and the case, thereby, to speak in exact terms, making the bntment va pistou-wheel of smaller size and capacity of work than the main piston-wheel H.

The effect of this construct-ion is to throwl a small amount of work upon the bntment, or smaller pistonwheel, since the extended teeth r c carry rounds-.a small quantity of water at each revolution. I

This work, put upon the bntment, or smaller pistonwhe'el, produces a continual back pressure ou the butment, and if this back pressure is greater than the pulsating variation between the forward and reaction pressure of the mainstream of water, it will obviously prevent the vibration of the bntment or smaller vpiston-wheel. v,

The extent of projection given to the teeth fr'o' should not greatly exceed what is necessary to prevent lthe vibration, since all work put upon the bntment, or smaller piston-wheel beyond what is necessary for this purpose, is injurious. It need never exceed onethird the projection of the pistons h 71. of the pistonwheel H beyond its gear-teeth m m, as indicated in the drawings, 'and unless the pressure in the pump is veg great, it may be muchless than that proportion.

e extended teeth c' lr fit luto suitable enlarged cavities s s in the piston-wheel H, substantially as shown, toallow their passage by the piston-wheel.

Another feature of improvement consists in the extension of the rear bearings p pof the pistou and bntment-shafts C D beyond the case, substantially as shown in tig. 2.

By this construction I obtain a longbearing-surice l for the journals of the sha-ft, thereby diminishing the wear of the journals and bearings.

I usually line the projections p 1) with Babbit metal, as at t t, fig. 2.

Close tubes, u u, surround the shafts C D, where they extend through the water-chambers G "T, as shown. These increase the extent of the journalbearings.

These extended bearings, projecting from this faceplate a of the case, also give additional support to the shafts, and take away a great part of the strain from the partition E, between the water-chamber and pist0n-chamber.

What I claim as my invention,'and desire to secure by Letters Patent, is-

The two piston-wheels H I, of unequal size, and constructed as described, and arranged and operating in combination, substantially as and for the purpose herein specified.

I also claim the combination of the projecting bearings p 11, outside of the wateuchambers Gr T, and the close tubes u u, extending through the said waterchambers, substantially as `and for the purposes set forth. 1

The abovel specification of my improved rotary pump signed by me, this 25th day of January, 1866.`

A. H. KNAPP.

Witnesses:

J. S. BROWN, A. J. HoYcr. 

